/* Copyright (C) 2001-2015 Peter Selinger.
 *  This file is part of Potrace. It is free software and it is covered
 *  by the GNU General Public License. See the file COPYING for details. */

#ifndef BITMAP_H
#define BITMAP_H

#include <string.h>
#include <stdlib.h>
#include <errno.h>

/* The bitmap type is defined in potracelib.h */
#include "potracelib.h"

/* The present file defines some convenient macros and static inline
 *  functions for accessing bitmaps. Since they only produce inline
 *  code, they can be conveniently shared by the library and frontends,
 *  if desired */

/* ---------------------------------------------------------------------- */
/* some measurements */

#define BM_WORDSIZE ( (int) sizeof(potrace_word) )
#define BM_WORDBITS (8 * BM_WORDSIZE)
#define BM_HIBIT    ( ( (potrace_word) 1 ) << (BM_WORDBITS - 1) )
#define BM_ALLBITS  (~(potrace_word) 0)

/* macros for accessing pixel at index (x,y). U* macros omit the
 *  bounds check. */

#define bm_scanline( bm, y )    ( (bm)->map + (ssize_t) (y) * (ssize_t) (bm)->dy )
#define bm_index( bm, x, y )    (&bm_scanline( bm, y )[(x) / BM_WORDBITS])
#define bm_mask( x )            ( BM_HIBIT >> ( (x) & (BM_WORDBITS - 1) ) )
#define bm_range( x, a )        ( (int) (x) >= 0 && (int) (x) < (a) )
#define bm_safe( bm, x, y )     ( bm_range( x, (bm)->w ) && bm_range( y, (bm)->h ) )
#define BM_UGET( bm, x, y )     ( ( *bm_index( bm, x, y ) & bm_mask( x ) ) != 0 )
#define BM_USET( bm, x, y )     ( *bm_index( bm, x, y ) |= bm_mask( x ) )
#define BM_UCLR( bm, x, y )     ( *bm_index( bm, x, y ) &= ~bm_mask( x ) )
#define BM_UINV( bm, x, y )     ( *bm_index( bm, x, y ) ^= bm_mask( x ) )
#define BM_UPUT( bm, x, y, b )  ( (b) ? BM_USET( bm, x, y ) : BM_UCLR( bm, x, y ) )
#define BM_GET( bm, x, y )      (bm_safe( bm, x, y ) ? BM_UGET( bm, x, y ) : 0)
#define BM_SET( bm, x, y )      (bm_safe( bm, x, y ) ? BM_USET( bm, x, y ) : 0)
#define BM_CLR( bm, x, y )      (bm_safe( bm, x, y ) ? BM_UCLR( bm, x, y ) : 0)
#define BM_INV( bm, x, y )      (bm_safe( bm, x, y ) ? BM_UINV( bm, x, y ) : 0)
#define BM_PUT( bm, x, y, b )   (bm_safe( bm, x, y ) ? BM_UPUT( bm, x, y, b ) : 0)

/* free the given bitmap. Leaves errno untouched. */
static inline void bm_free( potrace_bitmap_t* bm )
{
    if( bm )
    {
        free( bm->map );
    }

    free( bm );
}


/* return new un-initialized bitmap. NULL with errno on error.
 *  Assumes w, h >= 0. */
static inline potrace_bitmap_t* bm_new( int w, int h )
{
    potrace_bitmap_t* bm;
    int dy = w == 0 ? 0 : (w - 1) / BM_WORDBITS + 1;
    ssize_t size = (ssize_t) dy * (ssize_t) h * (ssize_t) BM_WORDSIZE;

    /* check for overflow error */
    if( size < 0 || size / h / dy != BM_WORDSIZE )
    {
        errno = ENOMEM;
        return NULL;
    }

    bm = (potrace_bitmap_t*) malloc( sizeof(potrace_bitmap_t) );

    if( !bm )
    {
        return NULL;
    }

    bm->w   = w;
    bm->h   = h;
    bm->dy  = dy;
    bm->map = (potrace_word*) malloc( size );

    if( !bm->map )
    {
        free( bm );
        return NULL;
    }

    return bm;
}


/* clear the given bitmap. Set all bits to c. */
static inline void bm_clear( potrace_bitmap_t* bm, int c )
{
    /* Note: if the bitmap was created with bm_new, then it is
     *  guaranteed that size will fit into the ssize_t type. */
    ssize_t size = (ssize_t) bm->dy * (ssize_t) bm->h * (ssize_t) BM_WORDSIZE;

    memset( bm->map, c ? -1 : 0, size );
}


/* duplicate the given bitmap. Return NULL on error with errno set. */
static inline potrace_bitmap_t* bm_dup( const potrace_bitmap_t* bm )
{
    potrace_bitmap_t* bm1 = bm_new( bm->w, bm->h );
    ssize_t size = (ssize_t) bm->dy * (ssize_t) bm->h * (ssize_t) BM_WORDSIZE;

    if( !bm1 )
    {
        return NULL;
    }

    memcpy( bm1->map, bm->map, size );
    return bm1;
}


/* invert the given bitmap. */
static inline void bm_invert( potrace_bitmap_t* bm )
{
    ssize_t i;
    ssize_t size = (ssize_t) bm->dy * (ssize_t) bm->h;

    for( i = 0; i < size; i++ )
    {
        bm->map[i] ^= BM_ALLBITS;
    }
}


#endif /* BITMAP_H */
